The present application claims priority under 35 U.S.C. xc2xa7119 of German Patent Application No. 100 50 596.1, filed on Oct. 12, 2000, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The instant invention relates to a deflection controlled roll having a rotatable roll jacket and a rotationally fixed carrier arranged within the roll jacket. A hydraulic support element arrangement is positioned between the carrier and the roll jacket, and a closed bearing ring is provided in a respective end region of the roll jacket and is movable in a press plane relative to the carrier. A bearing arrangement is positioned between the bearing ring and the roll jacket.
2. Description of Related Art
Such a deflection controlled roll is known from, e.g., EP 0 332 549B 1. The roll jacket rotates around the rotationally fixedly supported carrier in operation. Deflections resulting on an appropriate loading of the roll jacket are absorbed by the hydraulic support element arrangement. This supports the roll jacket with respect to the carrier from the inside. While a deflection of the carrier can also occur here, the elastic line of the roll jacket can be appropriately better influenced.
The support element arrangement can, however, only absorb forces which act in a press plane extending through the press gap or nip formed with a counter surface. The relevant forces can therefore be produced, for example, by a counter-roll or a roll stack downstream thereof. In addition, the roll jacket must be held on the carrier by a bearing which permits a rotation of the roll jacket with respect to the carrier and simultaneously allows a certain jacket positioning.
The relevant bearing arrangement is now exposed to different loads in different situations. The roll jacket is supported by the hydrostatic support elements with respect to the carrier in operation. The bearing arrangement can thus be held practically free of support forces at least with a vertically aligned roll stack in which the support elements between the carrier and the roll jacket also produce a vertically aligned force component. The roll jacket""s own weight and the forces applied by the other rolls and acting in the press direction are absorbed by the support elements between the roll jacket and the carrier. The bearing arrangement in this case serves practically exclusively for the positioning of the roll jacket with respect to the carrier. If, in contrast, the press nip of the roll stack is opened, then the weight of the roll jacket rests on the bearing arrangement. In this case, the bearing arrangement must be able to absorb the jacket weight, and indeed also with a rotating roll jacket. It must in all cases be ensured that the bearing arrangement runs with as little play as possible which may not exceed a pre-determined measure.
With the previously known deflection controlled rolls of the kind initially mentioned, the bearing is formed by roll bodies. Such roll bearings, however, now have the disadvantage that they no longer work with the required reliability with the rolls which run increasingly faster.
The invention present invention provides an improved deflection controlled roll of the kind initially mentioned which is safe and works reliably in particular also at higher operating speeds.
Accordingly, the invention includes a bearing arrangement having at least two hydrostatic support elements which are mutually spaced in the peripheral direction and of which at least one is movable relative to the carrier; and in that at least one force generating device, which acts generally radially in the press plane and radially penetrates the bearing ring, that is arranged between the carrier and the roll jacket.
It is possible due to this embodiment to operate a respective deflection controlled roll with a jacket stroke also at higher speeds, that is at peripheral speeds in the order of magnitude of, e.g., about 2,000 m/min. A defined support is possible in different radial directions by an appropriate distribution of the support elements associated with the bearing arrangement, with additional forces being able to be applied to the roll jacket in the bearing region via the force generating device penetrating the bearing ring. Since at least one, preferably more or even all support elements, can be movable with respect to the bearing ring, they are in a position to adjust themselves even with diameter changes of the roll jacket and/or of the bearing ring or of the carrier, which by no means have to develop in the same way, and thus to ensure that the roll jacket is always supported to the desired degree. Play such as is known from rolling bearings and which can result in an unfavorable vibration behavior in operation under certain circumstances, is kept extremely small with this kind of support. The hydrostatic support of the roll jacket in the region of the rotation bearings furthermore allows relatively low-wear operation, and indeed also at higher speeds.
While in a press roll known from, e.g., DE 29 42 002 C2, a support ring having hydrostatic support elements arranged at its periphery is already provided, this support ring is arranged in a middle roll region. Moreover, this support ring is stressed by force generating devices arranged between it and the carrier.
In a preferred practical embodiment of the deflection controlled roll of the invention, at least one hydrostatic support element each is provided at both sides of the press plane, with in particular at least two such support elements each being provided at each side.
It is also advantageous if at least some of the hydrostatic support elements are arranged pair-wise at mutually opposite bearing ring sides and the two support elements of each pair have mutually opposite radial directions of effect.
In a further appropriate embodiment of the deflection controlled roll of the invention, two force generating devices acting in opposite radial directions are provided on mutually opposite carrier sides.
Preferably at least one force generating device is formed by a respective hydraulic piston-in-cylinder arrangement.
The bearing ring is expediently rigidly designed. It is advantageously dimensioned such that a ring gap remains between the carrier and the bearing ring when these are in a mutually coaxial arrangement. As a consequence of the rigid, closed bearing ring, the forces occurring with any roll deformations are transferred via this ring from the one side to the other and from there again to the roll jacket without a support at the inner carrier occurring. A kind of expanding ring is formed by which the roll jacket is expanded. A support at the inner carrier should therefore not normally take place. A support of the bearing ring at the carrier can only take place with occurring tangential forces and tilt movements accompanying these and with other forces acting from the outside. Corresponding external forces can occur, for example, with a horizontal roll arrangement having overhead stabilizing elements which carry the roll weight and with the use of an external scraper, by which, however, only minor forces are produced.
In a preferred practical embodiment of the deflection controlled roll of the invention, the movable support element has a bearing pocket arrangement whose effective surface is larger than a surface of the support element onto which a pressure between the bearing ring and the support element is effective. It is thereby ensured that while the support element can be pressed into the bearing ring with a certain force when appropriate forces act on the roll jacket, the force with which the support element contacts the bearing ring is limited since hydraulic pressures build up above and beneath the support element. The magnitude of said force can be influenced by the surface difference. Thus, a stable support results even with changing diameters of the roll jacket. It is practically ensured that the roll jacket always slides on a fluid film.
The support element can preferably be moved into the bearing ring up to the lock position under load. Since no relative movement arises between the ring side end face of the support element and the bearing ring which results in friction, such a moving in of the support element xe2x80x9cup to the abutmentxe2x80x9d can be accepted. The roll jacket is supported in operation, for example, by the support elements between the carrier and the roll jacket or also by further rolls which are arranged beneath the roll jacket and which form a nip with the deflection controlled roll. In this case, the bearing arrangement is practically free of external support forces. It mainly serves to position the roll jacket with respect to the carrier. It is possible as a result of the at least one movable support element between the bearing ring and the roll jacket to design the bearing arrangement with very low play. The support elements can also be held in direct proximity to the inside of the roll jacket while forming a fluid film of the hydraulic fluid.
In a preferred practical embodiment of the deflection controlled roll of the invention, the bearing packet arrangement is connected to a supply device which provides a constant volume flow of hydraulic fluid, with the bearing pocket arrangement expediently being connected to a pressure space provided between the support element and the bearing ring via a capillary arrangement penetrating the support element.
As a result of the supply of the bearing pocket arrangement with a constant volume flow, the pressure above the relevent support element increases as the load increases so that an equilibrium of forces again comes about, with a constant pressure loss resulting between the pressure space beneath the support element and the pocket arrangement on its surface by the capillary arrangement penetrating the support element. For this reason, the pressure in the pressure space under the support element also increases as the pocket pressure increases. For the event of a support element moved into the bearing ring up to the lock position under a load, this again means that the force which is applied by the contact of the support element at the base of the pressure space is in any case very small. It depends on the ratio of the effective surface of the bearing pocket arrangement to the pressure-loaded surface of the support element at the side of the bearing ring. With a usual surface ratio of, e.g., about 1:1, the contact force only amounts to about {fraction (1/10)} of the support source force or support element force. Thus, it can be ensured by the constant volume flowxe2x80x94independent of the respective loadxe2x80x94that the support function is maintained for each support element, and indeed also when the support element is moved into the bearing ring up to the lock position. It is accordingly always ensured that a fluid film is maintained between the support element and the roll jacket.
The capillary arrangement is preferably dimensioned such that a predetermined pre-tension force is not exceeded in the unloaded state, but that a predetermined gap height is ensured with a pre-determined load. The unloaded state can be easily determined. The capillary arrangement is dimensioned such that a sufficient quantity of hydraulic fluid can flow to the bearing pocket arrangement in the unloaded state so that the pressure in the pressure space does not exceed a pre-determined value. Too high a strain of the roll jacket in the unloaded state is thus prevented. Vice versa, the restriction resistance of the capillary arrangement may not be too small so that it is ensured at any load that a gap having a pre-determined order of magnitude is maintained between the support element and the roll jacket.
The supply device can in this respect be matched to the capillary arrangement, for example, such that a minimum gap in the region of, for example, about 20 to about 30 xcexcm results between the support element and the roll jacket at maximum load. Such a gap is sufficient to prevent damage to the roll jacket by setting down on the support element. However, it is tight enough to sufficiently restrict the oil flow through the support element so that the fluid consumption is kept in an acceptable range.
It is also of advantage if the movable support element(s) have a lift with respect to the bearing ring in the radial direction which corresponds at least substantially to a maximum change resulting from thermal diameter differences and/or roll jacket deformations or carrier deformations due to nip loads. Therefore, the lift can be restricted to very small values.
The stroke must only be so large that it can compensate the changes which result from thermal diameter differences and deformations of the roll jacket or of the axles due to nip loads. The stroke of a respective support element can in particular correspond roughly to the bearing play of a conventional rolling bearing. This lift can, for instance, be in a range from, e.g., about 0.1 to about 0.5 mm, which substantially corresponds to the play of a C3 self-aligning roller bearing, with it being ensured by the lift that just no play occurs with the support in accordance with the invention.
In an appropriate embodiment, the ring-side end face of at least one support element is bent. Such an embodiment is expedient in particular when the relevant support element is moved into the bearing ring up to the lock position with a corresponding load. It is avoided by the bent support surface that the support element contacts the base of the cylinder space or of the pressure space with an edge when the carrier is bent by a corresponding load. Thus, the wear is correspondingly reduced. Furthermore, a hydrostatic bearing results for a roll with jacket stroke which meets the demand of a bending carrier in a relatively good manner. The support element moved into the bearing ring can roll off on the base of the cylinder space or have areal contact in the base region of the cylinder space despite the possibility of an inclination. The support element can, for instance, be arranged in a cylinder space, e.g., whose base is bent or curved in a complementary manner with respect to the end surface of the cylinder element. The complementarily bent or curved base surface can be formed, e.g., by an appropriate insert in the relevant cylinder bore.
However, it is also possible to arrange the relevant support element in a cylinder housing which has a concavely arched base which is supported on a correspondingly convexly curved surface at the carrier. In this case, too, a full-area support is optionally achieved while maintaining the possibility of an inclination.
It is of advantage if a bearing ring is preferably axially supported at the roll jacket at its side facing the relevant roll end via at least on a hydrostatic support element. The bearing ring can alternatively or additionally axially contact the roll jacket via hydrostatic slide surfaces. A fixed bearing can be realized at the relevant axial roll end in this manner. The bearing ring is expediently supported at the carrier in a tiltable and/or radially movable manner at its opposite side.
A spring, which can in particular be a disk spring, is advantageously arranged between at least one movable support element and the associated bearing ring. As already mentioned, the support elements are preferably subjected to a constant volume flow which also enters into the bearing pockets. The support elements preferably only have a low stroke in the bearing ring, which corresponds, e.g., roughly to the bearing play of a conventional rolling bearing. In the event of a sufficiently large applied bearing force, the loaded support elements move into the bearing ring to abutment or into the lock position. In this case, the pressure above the support element increases until the equilibrium of forces is reached. Since the pressure under the support elements also increases due to the constant volume flow, the contact force of the support element at the bearing ring is very small in proportion to the overall force which the support element absorbs. As already mentioned, it depends on the ratio of the effective area of the bearing pocket arrangement and the ring-side end face of the support element subjected to pressure. With a usual surface ratio of, e.g., about 1.1, the contact force only amounts to about 10% of the support element force. It is possible by this big ratio of transmission to take up the force absorption under the support element by a commercial elastic spring, e.g., a disk spring, whichxe2x80x94as results from the followingxe2x80x94provides a series of further advantages.
The spring characteristic of the bearing can be individually designed by an elastic bedding of the support elements. A support element which can move freely produces a constant support force with a constant volume flow over the path. If the support element moves against a rigid abutment, the forces can increase without a practical change in path. With the bedding of the support element on a spring, a linear force path characteristic is obtained. If the spring is already biased during the assembly of the individual bearing parts, a play-free bearing is obtained.
In this respect, the respective support element can have, e.g., an abutment movable parallel to the spring, which comes into contact with the bearing ring after a pre-determined spring path. The force path characteristic of the support element can be individually designed with this embodiment. With a bedding of the support element on a spring, the already mentioned linear force path characteristic is obtained. If the support element moves, in contrast, into the lock position in which the abutment comes into contact with the bearing ring, then the forces can increase without a practical path change. A spring characteristic can therefore be set in wide limits by a combination of these two cases.
If the maximum spring path is, e.g., shorter than the maximum stroke of the support element, then a further property can be integrated into the force path development. A support element that can move freely namely produces a constant application force over the path. Therefore, if the force path ratios are combined with the constant power force development, then three different sections can already be realized in the force path relationship.
Accordingly, the instant invention is directed to a deflection controlled roll that includes a rotatable roll jacket, a rotationally fixed carrier arranged within the roll jacket, and a hydraulic support element arrangement positioned between the carrier and the roll jacket. A closed bearing ring is located in an end region of the roll jacket and is movable relative to the carrier in a press plane, and a bearing arrangement is positioned between the bearing ring and the roll jacket. The bearing arrangement includes at least two hydrostatic support elements which are mutually spaced in a peripheral direction and at least one of the at least two hydrostatic support elements is movable relative to the carrier. At least one force generating device is positioned between the carrier and the roll jacket and is arranged to act generally radially in the press plane. The at least one force generating device is located to radially penetrate the bearing ring.
In accordance with a feature of the instant invention, the at least two hydrostatic support elements can be provided on opposite sides of the press plane. The at least two hydrostatic support elements may include at least two support elements positioned on each side of the press plane.
The at least two hydrostatic support elements can include a support element pair, in which individual support elements of the support pair may be located on mutually opposite bearing ring sides, relative to the press plane, and may be arranged to act in mutually opposing radial directions.
The at least two hydrostatic support elements may include a plurality of support element pairs, in which individual support elements of each pair can be located on mutually opposite bearing ring sides, relative to the press plane, and can be arranged to act in mutually opposing radial directions.
The at least one force generating device can include two force generating devices arranged at mutually opposite carrier sides, relative to the press plane, which act in opposing radial directions.
According to another feature of the invention, the at least one force generating device may include a hydraulic piston in cylinder arrangement.
In accordance with still another feature of the present invention, the bearing ring can be rigidly designed.
The bearing ring and the carrier can be coaxially arranged to form a ring gap between the carrier and the bearing ring.
According to a further feature of the invention, the support elements can include a bearing pocket arrangement having an active surface larger than a pressure surface of the support element onto which a pressure between the bearing ring and the support element acts. The support elements may be movable into the bearing ring up to the lock position under load. Further, the bearing pocket arrangement may be to a supply device which supplies a constant volume flow of hydraulic fluid. The bearing pocket arrangement can be coupled to a pressure space formed between the support element and the bearing ring through a capillary arrangement arranged to penetrate the support element. Moreover, the capillary arrangement can be formed such that a pre-determined pre-tension force is not exceeded in the unloaded state, and a pre-determined minimum gap height can be ensured with a pre-determined load. Still further, the support elements can be a lift in a radial direction with respect to the bearing ring. The lift may at least substantially correspond to a maximum change which results from at least one of (A) thermal diameter differences and (B) one of roll jacket deformations and carrier deformations due to nip loads.
Moreover, a ring-side end face of at least one of the support elements can be curved. The at least one support element can be arranged in a cylinder space having a base which is curved in a complementary manner to the end face of the at least one support element.
The bearing ring may be axially supported at an end of the roll jacket via at least one of at least one hydrostatic support element and at least one hydrostatic slide surface. The bearing ring can be axially supported at the roll jacket at a side facing the bearing ring end via at least one hydrostatic support element. Further, another bearing ring can be positioned at an opposite end region of the roll jacket, and the another bearing ring may be supported at the carrier in at least one of a tiltable and a radially movable manner.
Further, a spring may be positionable arranged between at least one of the support elements and the bearing ring. The spring can include a disk spring.
The present invention is directed to a deflection controlled roll that includes a rotatable roll jacket, a rotationally fixed carrier arranged within the roll jacket, and closed bearing rings located in an end regions of the roll jacket and movable relative to the carrier in a press plane. A bearing arrangement is positioned between the bearing rings and the roll jacket, and the bearing arrangement includes at least one hydrostatic support element pair arranged so that individual support elements of the pair are positioned on opposite sides of the press plane. At least one force generating device is positioned between the carrier and the roll jacket and arranged to act generally radially in the press plane. The at least one force generating device is located to radially penetrate the bearing ring.
According to a feature of the invention, the individual support elements of the pair can be arranged radially opposite each other.
In accordance with yet another feature of the instant invention, the closed bearing ring may include a movable bearing located at one end region of the roll jacket and a fixed bearing located at the other end region of the roll jacket.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.